Muhammad I al-Mustansir

Muhammad I al-Mustansir (Abu Abd Allah Muhammad al-Mustansir ibn Yahya; 1228-1277) was the second ruler of the Hafsid dynasty in Ifriqiya and the first to claim the title of Khalif. Al-Mustansir concluded a peace agreement to end the Eighth Crusade launched by Louis IX of France in 1270. Muhammad I al-Mustansir had been a vassal of the Kingdom of Sicily, but had shaken off his allegiance when King Manfred was overthrown by King Charles I.

The Mamluk sultan Baibars had been attacking the remnant of the Crusader states in Syria. Baibars had seized the opportunity after a war pitting the cities of Venice and Genoa against each other (1256–1260) had exhausted the Syrian ports that the two cities controlled. By 1265 Baibars had captured Nazareth, Haifa, Toron, and Arsuf. Hugh III of Cyprus, nominal king of Jerusalem, landed in Acre to defend that city, while Baibars marched as far north as Armenia, which was at that time under Mongol control.

These events led to Louis' call for a new crusade in 1267. Louis was soon convinced by his brother Charles I, King of Naples and Sicily, to attack Tunis first, which would give them a strong base for attacking Egypt, the focus of Louis' previous crusade as well as the Fifth Crusade before him, both of which had been defeated there. Muhammad I al-Mustansir was rumored to be sympathetic to Christianity by way of his connections with Christian Spain and was considered a good candidate for conversion. Accordingly, Charles suggested to his brother that the arrival of a crusade in his support might bring about al-Mustansir's conversion. Thus it was that Louis directed the Eighth Crusade against Tunis.

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